During the "mirror" scene in the intro, I notice Patty is wearing a very dark hair color. How long did Patty have this shade of hair, and does anybody know why the show had her dye her hair?

She only had dark hair when she filmed the pilot,Who's choice it was to color her hair is anyone's guess.......

You mean "whose." "Who's" is an abbreviation for "who is."

Well I just read Patty's autobiography and she notes she did change her hair after the pilot, but doesn't explain why. She does mention that the Cathy was much more different than Patty in the early stages of show (including a much heavier accent), but they realized that just got in the way so they dumped a lot of that stuff.